WO 99/46501 discloses a device for filtering intake air of an internal combustion engine. The device comprises a housing that is closed by a cover. In the housing, a hollow-cylindrical filter element is arranged. The filter element is comprised of a zigzag-folded filter medium. The filter medium is arranged on a support body that is configured like a diffusor. One half of the support body is closed. The support tube tapers toward the center and the other half is provided with support rings for supporting the filter medium. Between the support rings there are passages for the intake air.